Arrangement for centering a bearing unit of a pull-type clutch

ABSTRACT

Upon fitting of a so-called pull-type clutch between engine and gearbox in vehicles, difficulties arise in achieving correct coupling between the declutching mechanism and the declutching bearing during bringing together of engine and gearbox. A bearing unit including a declutching bearing is freely rotatable in a pre-assembled condition and needs to be centered in a certain angular position for correct coupling to be obtained. In order to achieve this centering of the angular position of the bearing unit it is proposed according to the invention that the bearing unit is connected to a housing, which is fixed relative to the engine, via an extensible element by which the angular position may be fixed.

The present invention relates to an arrangement for centering theangular position of a bearing unit for a declutching bearing.

So-called pull-type clutches on the drive units of motor vehicles haveadvantages with regard to function, service life and manufacturing costswhen compared with so-called push-type clutches. The latter, however,have the advantage that they can be fitted simply when engine andgearbox are brought together, since the declutching mechanism only hasto press on the declutching bearing.

With a pull-type clutch, on the other hand, a coupling is requiredbetween the declutching bearing and the declutching mechanism. Since itis difficult, when engine and gearbox are brought together, to reach thedeclutching bearing and the declutching mechanism from the outside, itis desirable that the coupling as well as the uncoupling of these takesplace substantially automatically.

In the event that the declutching mechanism includes a declutching fork,its legs must then be moved, while engine and gearbox are broughttogether, into a position behind the lugs or the like which aregenerally found formed on the declutching bearing for interaction withthe legs.

A solution for achieving this is previously known from Swedish patentapplication No. 8501248-2. In this wire spring arranged on thedeclutching bearing is used to interact with the legs of the declutchingfork. With the rotatable declutching bearing and with it the wire springin a pre-set angular position, the legs of the likewise pre-setdeclutching fork are then caused to move towards the wire spring, whileengine and gearbox are brought together, so that the legs of the forkare moved to a position behind the lugs of the declutching bearing.

The known solution referred to has disadvantages when applied to freelyrotatable declutching bearings which, as a consequence of anonsymmetrical construction, can scarcely be pre-set in the angle ofrotation position which is required in order that the desiredinteraction with the declutching fork can take place.

The aim of the present invention is to achieve an arrangement as statedat the outset in which the disadvantages referred to are eliminated. Tothis end the invention is directed toward an extensible elementconnected to the bearing unit, and also connected, for example, to thehousing around the engine, for action upon the bearing unit to set anangular position of the bearing unit. The bearing unit is an assemblywhich is preassembled to and is rotatable relative to the clutch. Theobjective is to prevent the bearing unit from freely rotating and to setthe angular orientation of the bearing unit.

By virtue of the presence of the connecting element, which is referredto there and which fixes the angular position, between the declutchingbearing housing and the housing which is fixed relative to the engine,the declutching bearing can be pre-set at the precise angular positionin which to be correctly brought together with the legs of thedeclutching fork. The displaceability of the declutching bearing whichis necessary for the declutching movement during normal operation of thevehicle can be achieved, notwithstanding the connecting element, byvirtue of the stated extensibility.

A further aim of the present invention has been to integrate, by meansof the connecting element, a lubricant transfer to a sliding bearingsituated in the declutching bearing. In one embodiment of the invention,therefore, the connecting element includes a flexible pipe which makesit possible to supply lubricant to the sliding bearing of thedeclutching bearing from outside.

Other features characterizing the invention emerge from the accompanyingpatent claims and the following description of an embodimentillustrating the invention. In the description reference is made to theaccompanying figures in which

FIG. 1 shows partial schematically reproduced view from above of anarrangement according to the invention before an imminent bringingtogether of engine and gearbox,

FIG. 2 shows the said arrangement after bringing together, and

FIG. 3 shows essentially a section along A--A in FIG. 1.

It can be seen from FIG. 1 how a bearing unit 1 for a declutchingbearing 2 is pre-assembled. The arrangement shown in the figurescomprises a clutch 2 which is mounted on an engine 1 and which isbrought, from a position before bringing together, by means of an axle 3moving into a gearbox 4 and also by means of a declutching fork 5mounted on the gearbox to an assembled operating position according toFIGS. 2 and 3. The clutch 2 according to the arrangement according tothe invention is of the conventional friction disc type which does notconstitute part of the present invention and is consequently notdescribed in greater detail here. It can be seen from FIGS. 1 and 2 howthe clutch 2 is surrounded by a flywheel housing 6 which is fixed to theengine 1. A diaphragm spring 8, which is nonrotatably connected to theflywheel 7 of the engine in a conventional manner which is not describedhere in greater detail, is attached centrally to the one inner ball race10 of the declutching bearing 9. The other outer ball race 11 of thedeclutching bearing is firmly fixed in a housing 12 which has a radiallyinward-turned cylindrical casing surface 13. Together with thedeclutching bearing 9 the housing 12 is henceforward referred to as thebearing unit 15.

The bearing unit 15 has an axial cylindrical hole running through itwhich is limited by the casing surface 13 and through which the inwardmoving axle 3 of the gearbox extends. Furthermore, the housing 12 of thebearing unit is provided with radially projected lugs 16, one on eachside of the housing. In between the housing is designed with a guideelement 17 in the form of two legs 18 which are positioned radially andin a peripheral direction at a distance from one another. The said lugs16 and the guide element are intended to interact with the declutchingfork 5 which is fixed to the gearbox. The fork is pivotably mounted on abearing bracket 19 which is fixed to the end wall 20 of the gearbox. Thebearing bracket 19 is designed with a guide boss 21 which engagesbetween the legs 18 of the guide element 17 in order to prevent turningof the bearing unit 15 during operation.

In addition, the bearing unit 15 is provided with a radial boring (notshown). To this is fixed a connection 22 to a tube 23 for the supply oflubricant via the boring to the hole through the bearing unit 15. Thecylindrical inner surface 13 of the hole in fact forms a sliding bearingtogether with a stay tube 24 which encloses the axle 3 and is fixed tothe gearbox 4. The said sliding bearing makes possible axialdisplaceability between the bearing unit 15 and the stay tube 24 forcarrying out the necessary declutching movement during normal operationof the vehicle.

The supply of lubricant is intended to take place at predeterminedservice times for the vehicle. To the tube 23, therefore, a flexiblehose 25 is attached which, at its radially outer end, is connected via afurther tube 26 to a lubricator nipple 27 located outside the flywheelhousing. Parallel with the hose 25 a tension spring 28 extends betweenthe metal tubes 23, 26. Both the hose 25 and the spring 28 are designedas an extensible element which, during operation, makes possible thenecessary declutching movement. In all positions, however, the tensionspring 28 exerts a tensile force between the tubes 23, 26 and thusexerts a force for fixing the angular position on the bearing unit 15.

The radially outer part of the declutching fork 5 passes through anopening 30 made for this purpose in a clutch housing 31 which is fixedto the gearbox. Outside the clutch housing 31 the outer end of thedeclutching fork interacts, in a way which is not shown here, with apiston rod issuing from a compressed air cylinder which is part of amanually actuable manoeuvring mechanism for the clutch.

The radially inner part of the declutching fork consists of two legs 32,33 which are intended to grip around the bearing unit 15. The ends ofthe legs 32, 33 are thus intended to interact with the lugs 16 of thebearing unit by assuming a position by the side of the lugs 16 which isturned away from the gearbox.

It can be seen from FIG. 1 how the declutching fork 5, before bringingtogether of the gearbox and engine, has been pulled back to its maximumrearward position. Both the declutching fork 5 and the extensibleelement 25, 28 have an essentially horizontal extension which has theeffect that the bearing unit 15, which is freely rotatable duringbringing together, tends to turn itself, under the influence of gravity,out of a correct angular position for bringing together. According tothe invention, however, the bearing unit 15 can be centred by attachingthe outer section of tube 26 of the lubricant pipe 23, 25, 26 to theflywheel housing in a pre-determined position. This can be done eitherby mounting the outer section of tube 26 in a pre-determined hole in theflywheel housing 6 or by providing the outer section of tube 26- as isthe case in the figures- with a catch 35 which can grip around the edgeof the flywheel housing 6 close by a pre-determined mark on the housing6.

The last-mentioned solution means that minor adjustments to the angularposition of the bearing unit 15 can be made simply from outside in orderto facilitate the passing of the declutching fork 5 between the legs 18of the guide element 17.

During bringing together the inward moving axle 3 of the gearbox 4 andits surrounding stay tube 24 are first passed into the hole in thebearing unit 15. The ends of the legs 32, 33 of the declutching fork 5are then moved to a position seen from the engine side in front of thelugs 16 of the bearing unit 15 according to FIG. 1 at the same time asthe guide boss 21 is moved in between the legs 18 of the guide element17. When bringing together is completed by the housings 6, 31 havingcome into contact with one another, the ends of the legs of thedeclutching fork are brought into contact with the lugs 16 by manualactuation of the manoeuvring mechanism of the clutch. In the clutchhousing a recess 36 is formed in which the tube 26 is accommodated whenthe housings 6, 31 make contact with one another.

The above exemplary embodiment is not intended to have a limiting effecton the invention but it can be modified, within the scope of thefollowing claims, in a number of embodiments. Thus, the extensibleelement 25, 28 between the bearing unit 15 and the flywheel housing 6does not necessarily have to contain a lubricant pipe if, for example,the sliding bearing between the bearing unit 15 and the stay tube 24 isof a permanently lubricated type. In such a case it can be designed withjust one extensible spring of the type shown in the figures or in theform of a plate spring. Nor does the extensibility in itself need to beachieved by means of a spring but can be achieved, for example, with adouble pivoted connecting element between the bearing unit 15 and theflywheel housing 6. The flexibility of the element should then simplymake possible the displaceability of the bearing unit 15 in an axialdirection but not allow any turning of the bearing unit 15 around theinward moving axle 3.

I claim:
 1. An arrangement for centering the angular position of abearing unit for a declutching bearing on a pull-type clutch, whereinthe clutch connects an engine, on the one hand, with a gear box, on theother hand, and wherein the gear box and the engine are initiallyseparated and are movable together, the clutch having an axis, theclutch being affixed to the engine for rotating therewith, thearrangement comprising:a bearing unit having an axis which is generallyparallel to the axis of the clutch, the bearing unit being rotatablearound its axis relative to the clutch, the bearing unit beingpreassembled to the clutch and thereby to the engine; a declutchingmechanism attached to the gear box, the declutching mechanism beingengageable with the bearing unit and cooperating with the bearing unitafter the gear box and the engine have been moved together; a housingfixed in position in relation to rotation of the engine; and anextensible element connected between the bearing unit and the housing,and a tension spring attached to the extensible element and maintainingthe extensible element in tension so that the extensible element fixesthe angular position of the bearing unit around its axis at apredetermined angular position so that the bearing unit is in anadjusted position suitable for receiving and connecting with thedeclutching mechanism prior to the bringing together of the gear box andthe engine; the declutching mechanism being movable from a position outof engagement with the bearing unit to a position in engagement with thebearing unit when the bearing unit is in the adjusted position.
 2. Thearrangement of claim 1, wherein the extensible element further includesa flexible pipe extending into the bearing unit for transferringlubricant through the pipe to the bearing unit, the spring beingconnected in parallel to the pipe at locations along the length of thepipe, the spring acting upon the bearing unit by acting upon theflexible pipe.
 3. The arrangement of claim 2, wherein the extensibleelement includes a non-flexible tube connected to the flexible pipe andextending from the flexible pipe to the fixed housing, the non-flexibletube having an inlet for lubricant.
 4. The arrangement of claim 3,wherein the bearing unit includes a sliding bearing therein and theflexible pipe is connected to the sliding bearing for delivery oflubricant.
 5. The arrangement of claim 3, wherein the fixed housing hasan edge, the extensible element including a catch for gripping the edgeof the housing in a preselected position along the edge of the housingangular position of the bearing unit.
 6. The arrangement of claim 1,wherein the fixed housing has an edge, the extensible element includinga catch for gripping the edge of the housing at a preselected locationalong the edge.
 7. The arrangement of claim 1, wherein the declutchingmechanism includes an arm pivotally supported on the gear box, the armincluding engaging means for engaging the bearing unit, the bearing unitincluding engageable means thereon for being engaged by the engagingmeans of the arm, the engageable means of the bearing unit being placedso as to be engageable by the engagement means of the arm only when thebearing unit is at a preselected angular orientation around its axis,and at that angular orientation, the arm can pivot into engagement on aside of the engageable means of the bearing unit facing away from thegear box.